Introduction to Frequently Asked Questions about pH Meter
1. What causes the two measurement data of the same sample to be different?
There are two situations that can cause the above problems:
(1) Temperature changes will cause differences in measured pH values. Please keep the measurement temperature unchanged.
(2) A chemical reaction has occurred in the sample itself, resulting in differences in measured pH values. Please measure the sample as soon as possible and pay attention to the storage conditions of the sample.
2. Why does it show 7.00 after calibration with pH6.86 buffer?
The wrong buffer group is selected and the correct buffer group needs to be reset (see the instrument operation manual). Or the buffer temperature is not at 25°C during calibration.
3. Why can’t the new electrode be calibrated or the value is unstable?
This may be due to the fact that there are bubbles in the electrode sensitive film or gel, resulting in abnormal potential changes. Therefore, the bubbles need to be removed. You can shake the electrode downwards with force (like a thermometer) to drive away the bubbles. If it is not used at ordinary times, you can hold the electrode upright. place. Or the electrode sensitive membrane has been left dry for too long and needs to be activated in 0.1mol/L dilute hydrochloric acid.
4. Why are the electrode measurement values unstable?
There are two situations that may cause the above problems:
(1) The electrode selection is inappropriate.
If the response time of the measurement buffer is very short but the measured sample is unstable, it means that the electrode is not suitable for measuring the sample to be measured (for electrode selection, please refer to the Appendix InLab Electrode Selection Guide).
(2) Electrode aging.
You can test the response time of the electrode in the buffer. If it is longer than 1 minute, the electrode needs to be activated (soaked in 0.1mol/LHCl overnight) or replaced with a new electrode.
